Best fit model “MCS” for the CS and C³⁴S molecular transitions. The black lines represent the observed spectra, while the red spectra are generated by the MAPYSO radiative transfer code. The dotted line shows the systemic velocity of Cha-MMS1 derived from a seven-component hyperfine fit to the N₂H⁺ 1−0 multiplet. For the APEX spectra, a correction of 0.1 km s^-1 was added (see Sect. 3.2.1). The angular separation of the different positions with respect to the central spectrum is shown on top of the respective spectra. The model assumes spherical symmetry, so the model spectra at symmetric positions are identical. The telescope used for conducting the obervations is shown at the leftmost box of each row. The spectra from left to right correspond to the south-east to north-west direction perpendicular to the filament.